Liquid fuel injection pumps



March 21, 1967 A. c. ROSSELLI 3,309,996

LIQUID FUEL INJECTION PUMPS Filed Feb. 26, 1965 2 Sheets-Sheet 1 March21, 1967 c, oss 9 3,309,996

LIQUID FUEL INJECTION PUMPS Filed Feb. 26, 1965 2 Sheets-Sheet 2 u. J"4v United States Patent 3,309,996 LIQUID FUEL INJECTION PUMPS AndrewCarlo Rosselli, Teddington, England, assignor to C.A.V. Limited, London,England Filed Feb. 26, 1965, Ser. No. 435,416 2 Claims. (Cl. 103-41)This invention relates to liquid fuel injection pumps for internalcombustion engines and has for its object to provide such a pump in aconvenient form.

According to the invention a liquid fuel injection pump comprises incombination a pump body, a cylindrical bore in the body, a co-axialcylinder at the inner end of the bore, an axially movable plunger in thebore, a piston formed or secured on the inner end of the plunger andacting within the cylinder, resilient means urging the plunger andpiston in a direction out of the bore and cylinder respectively, saidplunger and piston being adapted to be moved inwardly in timedrelationship with an engine with which the pump is associated, an outletpassage at the outer end of the bore adapted for connection to acylinder of the engine with which the pump is associated, a deliveryvalve in the outlet passage for preventing the flow of fuel from theoutlet passage into the bore, a fuel inlet passage at the inner end ofthe cylinder adapted to be uncovered by the piston near the outwardlimit of its stroke, a transfer passage through which the inner end ofsaid cylinder is in communication with a port in the wall of the boreintermediate the ends thereof, said port being positioned to beuncovered by the plunger as the latter nears the outward limit of itstravel, valve means in the transfer pas-sage for preventing the flow offuel from the bore to the-cylinder and for permitting the escape ofexcess fuel from the cylinder during inward movement of the piston, anda variable restrictor in the inlet passage, the arrangement being suchthat, in use, as the plunger and piston are moved outwardly by theresilient means voids will form in the fuel remaining in the bore andthe cylinder until the piston uncovers the inlet passage to allow fuelto fiow into the cylinder via the restrictor, whereafter when theplunger and piston are moved inwardly, the inlet passage will be closedby the piston and fuel will be displaced from the cylinder into the bonevia the transfer passage, the valve means, and the port, until thelatter is covered by the plunger whereafter fuel from the bore will bedischarged via the delivery valve and the outlet, and any excess fuel inthe cylinder will be allowed to escape via said valve means.

In the accompanying drawings:

FIGURE 1 is a diagrammatic view of one example of a liquid fuelinjection pump in accordance with the invention,

FIGURE 2 is a sectional side elevation of another example of a fuelinjection pump in accordance with th invention and FIGURE 3 is a viewtaken on the line 3-3 of FIG- URE 2.

In one example of the invention as shown in FIG" URE 1 there is provideda pump body in which is formed a cylindrical bore 11. At the outer endof the bore is an outlet 12 incorporating a non-return delivery valve13, and adapted for connection to a fuel injection nozzle (not shown) ofan engine. At the inner end of the bore there is formed in the body parta cylinder 14 which is of larger diameter than the bore and is formedco-axially therewith.

In the bore 11 is an axially movable cylindrical plunger 15 on which isformed, or secured, a piston 16 which occupies the cylinder 14. Theplunger and piston are urged outwardly by a coiled compression spring 17accommodated within the cylinder and are moved inwardly Patented Mar.21, 1967 in timed relationship with the engine with which the pump isassociated by means of a rotary cam 18 which acts on the outer end ofthe piston 16 through a follower 19.

At the inner end of the cylinder is a fuel inlet passage 20 which isadapted to be uncovered by the piston as the latter nears the outwardlimit of its travel and which communicates with a fuel inlet 20*.Moreover, the inlet passage contains an adjustable restrictor 21 for apurpose to be described.

Communicating with the outer end of the cylinder 14 is a transferpassage 22 by which the cylinder is in communication with a port 23 inthe wall of the bore 11, and the port is arranged to be uncovered by theplunger 15 as the latter moves outwardly. Within the transfer passage isa spring loaded non-return valve 24 which is positioned to prevent theflow of fuel from the bore to the cylinder. Moreover, a point in thetransfer passage 22, intermediate the valve 24 and the port 23, is incommunication with the inlet 20 by way of a further passage whichincorporates a non-return valve 25. This valve is arranged to preventthe flow of fuel from the inlet to the transfer passage.

The arrangement is such that as the plunger and piston are movedoutwardly by the spring 17 voids will form in the fuel remaining in thebore 11 and cylinder 14 until the inlet passage 20 is uncovered by thepiston. When this occurs fuel will flow into the cylinder from the inletvia the restrictor 21. If the rate of fuel flow past the restrictor issufficient, the cylinder will be filled com- 'pletely. However, no fuelwill flow past the non-return valve 24 since the strength of its springis sufficient to resist this. As the plunger and piston are movedinwardly by the cam 18 a small quantity of fuel will be spilled from thecylinder to the inlet passage 20 until the latter is covered by thepiston whereafter fuel will be displaced from the cylinder by the pistonand will flow, via the non-return valve 24, along the transfer passage22 and the port 23 into the bore. Fuel will continue to flow into thebore until the plunger 15 covers the port 23 whereafter with furtherinward movement of the piston the non-return valve 25 will be opened andexcess fuel remaining in the cylinder will be returned to the inlet 20.Moreover the fuel in the bore will be displaced by the plunger to theinjection nozzle past the delivery valve 13.

If the restrictor is set so that the cylinder 14 is not filledcompletely in the time available a reduced quantity of fuel will bespilled directly through the inlet passage 20 and eventually if therestrictor is set to reduce the flow rate sufficiently or the timeavailable for filling is reduced, as when the engine speed increases,there will be insufficient fuel in the cylinder to fill the bore and areduced quantity of fuel will be delivered to the engine. Thus, byvarying the restrictor the pump can be arranged to govern the enginewith which it is associated.

In order to control the maximum amount of fuel which can be delivered bythe pump a groove 26 is provided on the periphery of the plunger, theangular position of which is adjustable so that fuel may be spilled fromthe bore via the port and the transfer passage when the groove 26uncovers the port.

In a modification illustrated in FIGURES 2 and 3 there is provided apump body 30 in which is formed a stepped drilling. Within the drillingis mounted a barrel 31 and this is held against a step in the drillingby an adaptor 32. Within the barrel is formed an axial bore 33 and thiscommunicates with a fuel outlet 34 by way of a passage 35 defined in theadaptor. Moreover, the passage 35 contains a delivery valve 36.

Slidable Within the bore is a plunger 37 to which is secured a piston 38mounted in a cylinder constituted by 0 part of the stepped drilling.Furthermore, the plunger 37 is urged in a direction away from the outlet34 by a coiled compression spring 50 and is arranged to be moved inopposition to the spring by a cam (not shown), the cam being driven intimed relationship to the engine with which the pump is associated.

At the inner end of the cylinder in which the piston 38 is mounted is afuel inlet pasage 39 and this communicates with one end of atangentially disposed cylindrical chamber 40 formed in the body part,this end of the chamber communicating with a source of fuel. Furthermorethe inlet passage contains a one way valve 41 which is arranged toprevent the flow of fuel in a direction from the cylinder to the chamber40 and the passage 39 incorporates a restrictor which comprises anangularly adjustable plug 42. The inlet passage is arranged to beuncovered by the piston 38 as the latter nears the limit of its movementunder the influence of the spring.

The outer end of the aforesaid cylinder communicates by way of atransfer passage 43 with the other end of the chamber 40 and slidablymounted within this chamber is a cylindrical valve member 44. The valvemember is urged by a coiled compression spring 45 towards an adjustablestop 46 mounted in said other end of the chamber. Furthermore breakinginto the chamber 40 are a pair of passages 47 and 48. Passage 47communicates with the source of fuel and is arranged to be uncovered bythe valve member after passage 48 has been uncovered during movement ofthe valve member against the action of its spring as will be described.Passage 43 constitutes a transfer passage and is in communication withan annular gallery defined between the barrel 31 and the body part andbreaking into the gallery is a port 49 in the wall of the bore and whichis arranged to be covered by the plunger 37 during its movement by thecam.

In describing the operation of the pump it will be assumed that aninjection stroke has just been completed. During the return movement ofthe plunger voids will form in the fuel remaining in the bore 33 and inthe cylinder. However, when the piston 33 uncovers the passage 39 fuelwill flow into the cylinder at a rate dependent upon the setting of therestrictor 42. If the cylinder is completely filled then during inwardmovement of the plunger by the cam, fuel from the cylinder will passthrough the transfer passage 43 and will move the valve member 44 touncover the passage 48. When this occurs fuel will flow into the bore33, and this will be filled completely. During further inward movementof the plunger fuel from the cylinder will move the valve member touncover the passage 47 and the excess fuel will flow back to the fuelinlet. Moreover, at the same time when the port 48 has been closed, fuelwill be displaced to the outlet 34 and will flow to the associatedengine.

If the setting of the restrictor is such that insufficient fuel flowsinto the cylinder in the time available to fill the bore then thequantity of fuel supplied to the engine will be reduced. Hence as in theprevious example the maximum speed of the engine for a given setting ofthe restrictor will be governed. It will be appreciated that the amountby which the valve member must be moved before the passage 48 isuncovered will determine the maximum amount of fuel which can besupplied to the bore and consequently the adjustable stop 46 providesconvenient means of adjusting the maximum amount of fuel which can bedelivered to the engine.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid fuel injection pump comprising in combination, a pump body,a cylindrical bore in the body, a cylinder coaxial with the bore and atthe inner end thereof, an axially movable plunger slidable within thebore, and a piston mounted on the plunger and sliding within saidcylinder, first resilient means urging the plunger and piston out of thebore and cylinder respectively, said plunger and piston being adapted tobe moved inwardly in timed relationship with an engine with which thepump is associated, the swept volume of the plunger being less than thatof the piston, an outlet at the outer end of the bore, a delivery valvein said outlet for preventing the flow of fuel into the bore, a fuelinlet passage at the inner end of the cylinder, said inlet passage beingarranged to be uncovered by the piston near the outward limit of itsstroke, a port formed in the wall of the bore, said port being arrangedto be uncovered by the plunger near the outward limit of its travel, atransfer passage serving to connect the inner end of said cylinder withsaid port, a cylindrical chamber in the body part, a valve membermounted in said chamber, a second resilient means loading said valvemember in a direction towards one end of the chamber, said one end ofthe chamber communicating with said cylinder so that the pressure offuel in the cylinder will move the valve member against the action ofsaid resilient means, said transfer passage opening into said chamber ata position to be uncovered to said one end of the cylinder after aninitial movement of the valve member, and a further passage opening intothe wall of said chamber at a position to be uncovered to said one endof the chamber when the valve member has moved further, said furtherpassage allowing escape of excess fuel from said cylinder and a variablerestrictor in said inlet passage, said restrictor being arranged torestrict the rate at which fuel can flow through said inlet passage.

2. A liquid fuel injection pump as set forth in claim 1 includingadjustable stop means at said one end of the cylinder to limit themovement of the valve member under the action of the second resilientmeans.

References (Iited by the Examiner UNITED STATES PATENTS 1,171,825 2/1916Wood 103-153 1,760,237 5/1930 Iversen 103-168 1,943,162 1/1934 Coatalen103-168 2,841,085 7/1958 Evans 103-168 2,958,289 11/1960 Hafele 103-1543,058,455 10/1962 Hofer et al. 103-411 FOREIGN PATENTS 1,192,604 4/1959France.

DONLEY J'. STOCKING, Primary Examiner.

MARK NEWMAN, Examiner.

W. J. KRAUSS, Assistant Examiner.

1. A LIQUID FUEL INJECTION PUMP COMPRISING IN COMBINATION, A PUMP BODY,A CYLINDRICAL BORE IN THE BODY, A CYLINDER COAXIAL WITH THE BORE AND ATTHE INNER END THEREOF, AN AXIALLY MOVABLE PLUNGER SLIDABLE WITHIN THEBORE, AND A PISTON MOUNTED ON THE PLUNGER AND SLIDING WITHIN SAIDCYLINDER, FIRST RESILIENT MEANS URGING THE PLUNGER AND PISTON OUT OF THEBORE AND CYLINDER RESPECTIVELY, SAID PLUNGER AND PISTON BEING ADAPTED TOBE MOVED INWARDLY IN TIMED RELATIONSHIP WITH AN ENGINER WITH WHICH THEPUMP IS ASSOCIATED, THE SWEPT VOLUME OF THE PLUNGER BEING LESS THAN THATOF THE PISTON, AN OUTLET AT THE OUTER END OF THE BORE, A DELIVERY VALVEIN SAID OUTLET FOR PREVENTING THE FLOW OF FUEL INTO THE BORE, A FUELINLET PASSAGE AT THE INNER END OF THE CYLINDER, SAID INLET PASSAGE BEINGARRANGED TO BE UNCOVERED BY THE PISTON NEAR THE OUTWARD LIMIT OF ITSSTROKE, A PORT FORMED IN THE WALL OF THE BORE, SAID PORT BEING ARRANGEDTO BE UNCOVERED BY THE PLUNGER NEAR THE OUTWARD LIMIT OF ITS TRAVEL, ATRANSFER PASSAGE SERVING TO CONNECT THE INNER END OF SAID CYLINDER WITHSAID PORT,